1. Field of the Invention
The present invention relates to an image reading apparatus and a copying apparatus having the image reading apparatus.
2. Description of Related Art
Image reading apparatuses have been widely used for copying apparatuses and facsimile machines, etc. in which one reading section faces a transport path of original document, and conducts sequential reading of multiple original documents by sequentially passing multiple original documents through a reading position.
When reading each single face of the original documents, the sequential reading is conducted by simply transporting each of the multiple original documents sequentially. And when reading double faces of the original documents, a front face and a rear face of the original document are read by passing one original document twice through the reading position with using a switchback section. Further, in the case of double face reading, in order to realign the page order of the original documents after reading, each of the original documents is passed through the switchback section two times. In this way, the image reading apparatus, employing the double face reading function, conducts original documents transportation by twice employing the front/rear reversal operation for double face reading and page order realignment of the original documents.
As a the result, in an image reading apparatus having a double face reading function, the original documents transportation becomes somewhat complicated, the transport path becomes longer and the time required for image reading becomes also longer. Whereby, improving the reading speed becomes difficult.
In order to improve the speed in double face reading, Patent Document 1 and 2 propose image reading apparatuses which provide a reading section for each side of the original document transport path and conduct double face reading by simply transporting the multiple original documents sequentially.
Patent Documents 1 and 2 propose, in the image reading apparatus having two reading sections, to realize additional functions with the two reading sections. Patent Document 1 proposes a recovery function in case of failure in one of the reading sections, wile Patent Document 2 proposes a variety of reading functions.
Patent Document 1: Unexamined Japanese Patent Application Publication No. 2002-354192
Patent Document 2: Unexamined Japanese Patent Application Publication No. 2003-125168
According with improving performance in image forming apparatuses such as electrophotographic image forming apparatuses, demands for high-speed reading are increasing. Namely, not only improving the double face reading speed, as proposed in the Patent Documents 1 and 2, but also improving the single face reading speed is demanded.
It has been assumed that for improving the speed of the single face reading, very little room remains for modification of the original document transport path, contrary to the case of double face reading.
For example, improvement of the reading speed by way of increasing the transportation speed of the original document has limitation due to an inherent decrease of resolving power of the read image.
In apparatuses proposed by Patent Documents 1 and 2, the speed of double face reading is raised, however the speed of single face reading remains unchanged in generally used original reading apparatus described above.